11 research outputs found
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Local drift parameter, j/n/sub e/ and resistivity anomaly measurements in CTX spheromaks
In a spheromak, the magnetic fields confining the plasma are generated primarily by internal currents rather than external coils. In order to provide information on the possible existence of current-driven microinstabilities, localized measurements of the ratio of the drift velocity of the electrons generating the internal current to their thermal velocity, V/sub d//V/sub th/ proportional to j/n/sub e/..sqrt..T/sub e/ (known as the drift or streaming parameter), and j/n/sub e/ (proportional to V/sub d/) are needed. These microinstabilities are in some theories associated with an increase in the resistivity anomaly factor (eta/eta/sub Spitzer/). We present results on local measurements (at the magnetic axis) of the values of V/sub d//V/sub th/ and eta/eta/sub Spitzer/ by combining data from the spatially-resolved diagnostics employed on the CTX spheromak experiment, coupled with current density profile information from equilibrium measurements. The values of V/sub d//V/sub th/ and j/n/sub e/ appear to be correlated with local variations in eta/eta/sub Spitzer/, and can be changed by varying the plasma density. Data sets are presented for three values of n/sub e/
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Increased particle confinement with the use of external dc bias field in the CTX spheromak
Spheromaks are formed in a mesh flux conserver in the presence of an external dc bias field. The spheromaks remain stable to tilt instabilities with ratios of bias-to-spheromak flux of up to 47 +- 7%. Normally applied bias flux puts the spheromak separatrix inside the metal mesh and improves the particle confinement
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Determination of CTX equilibria
The method by which we determine the magnetic field equilibrium for CTX in a nonperturbing manner is presented. Measurements of flux conserver image currents are combined with calculations from a numerical model of the equilibrium. Results give equilibria which differ significantly from the minimum energy state, but the equilibria data are well-described by a model where j/B has a linear dependence on the poloidal flux function. The observation of non-disruptive rotating internal kink distortions (with toroidal mode numbers n = 1, 2 and 3) within the equilibria and theoretical MHD thresholds for the onset of these modes corroborate the inferred equilibria
Echinococcus granulosus: a seroepidemiological survey in northern Israel using an enzyme-linked immunosorbent assay
International audienceFollowing an intensive health education programme, 8651 finger-prick blood samples, 4122 from a predominantly adult group attending a primary care clinic and 4529 from schoolchildren, were collected in Tamra, northern Israel. An enzyme-linked immunosorbent assay (elisa) for immunoglobulin G (IgG) was used to detect anti-Echinococcus granulosus antibodies, using both crude and purified antigens. The seroprevalence in the adult group was 0·48% (graphic); optical density values were 0·1–0·14 in 10 subjects, 0·15–0·19 in 9, and ≥0·2 in one; prevalences did not differ significantly between males and females or among age groups. Twenty-six of the schoolchildren (0·57%) were seropositive, 23 with optical densities of 0·1–0·14, one of 0·15–0·19, and 2 ≥ 0·2. A high correlation was observed between elisa positivity and both positivity in the arc 5 immunoelectrophoresis test and the presence of a high titre in the indirect immunofluorescence assay. Cross reactivity was observed with sera from schistosomiasis and ancylostomiasis patients, using both crude and purified echinococcal antigens. The results indicated that the IgG elisa, using both crude and purified antigens, was very useful for seroepidemiological screening for echinococcosis, and that this condition is an emerging disease in northern Israel
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Results from the Los Alamos Fast Liner Experiment
Experimental results for aluminum liners imploded magnetically were obtained using a 1.75 MJ portion of the Scyllac capacitor bank at Los Alamos. Typical liner dimensions are 10-cm length, 5-cm diameter, and 1-mm initial thickness; because they are thick, these liners remain near solid density throughout the implosion. Implosion velocities of 4 to 6 x 10/sup 5/ cm/s have been consistently attained. These results agree well with theoretical calculations, which will also be presented. Results obtained with various diagnostics will be presented including voltage and current measurements, pin probes, magnetic field compression probes, and flash x-ray shadowgraphs